olson



July 10, 1923.

H. O. OLSON DEGIMAL EQUIVALENT Filed Jan. 5,

Patented July 10, 1923.

UNITED STATES HERBERT 0. OLSON, OF ROCKFORD DEGIMAL-EQUIVALENT C v Application filed January 3, 1920. Serial To all whom it may concern."

Be it known that I, HERBERT O. OLSON, a citizen of the United States, residing at Rockford, in the county of WVinnebago and State of Illinois, have invented certain new and useful Improvements in DecimaLEquivalent Charts, of which the following is a specification.

Engineers, mechanics, draftsmen and others who have occasion to frequently use numerical fractions and decimal equivalents thereof in their calculations, desire to obtain the decimal equivalents quickly and easily and with the least possible chance of confusion and error. To meet these require ments, tables have been provided containing columns of fractions with their decimal equivalents. These, however, are not entirely satisfactory, because of the difiiculty in being able to quickly pick out and read with certainty the desired decimal equivalent in a table of closely arranged figures.

The primary object of the present in- Vention is to provide a table or chart containing fractions and decimal equivalents thereof arranged in such novel manner as to enable the user to quickly and easily and without danger of confusion, read any fraction and its decimal equivalent.

Another object is to provide a chart of the character described, comprising rela tively shiftable top and bottom members, the former having closely associated denominator openings and a decimal-indicating opening, and the latter having numerators and decimal equivalents adapted to reg ister with said openings, whereby closely re lated portions and their decimal equivalents may be quickly ascertained by only a slight shifting movement of said members.

In furtherance of these general objects, I have illustrated a single embodimentof my invention, consisting of a top and bottom member pivotally associated as to be relatively rotatable, the top member having a plurality of openings therethrough, preferably in radial alignment, and a denominator below each of said openings, and the bottom member having a set of numerators for each of said denominators arranged in annular areas registering with the respective openings in the top member, whereby upon relatively rotating these members, any numerator may be positioned in the open- PAT ing above i in the provi posite, so t tion, its deci presented th 1 top member. e Other obj arrangement above-menti fully pointe tion becomes to the follow' siderpd in ca P 111g crawin 1 Figure bodying my Fig. 2, a f showing the 1 decimal equivn Fig. 3, a in an adjusted posi 31/32 and its i 1 As mentionqds templates theo. able top and r r which contailm series of fra lents thereof, on its face a S 4 nominators and with which adapted to tioning the d .w tained beneath ing in the p might be of might be rela manner for the In the present i ments, it is shall be pivotall tatable one upon of reg1ster1ng the top member with the bottom me members desi 4 and 5 respe together at 6 so i rotated. In the ton member. L I place a numeral I tor of a fraction. In the present case, the fractions to be transformed into decimal equivalents are eiths, Sths, lGths, 32nds and Glths, although it will be evidentthat other combinations of fractions might be used. However, this selection is particularly practical for draftsmen. The bottom member is divided into concentric areas registering respectively with the openings 7 and 8. In the innermost area A, I place the numerals 1 to 4: inclusive equally spaced apart, and in radial alignment with these numerals which represent numerators to the denominators i, I place the decimal equivalent in the marginal area B. Thus when the innermost opening 7 is registered with a numeral in the area A, as for instance with the numeral 4, as shown in Fig. 1, the fraction l/l appears, the decimal equivalent of which is 1.0, as shown in the opening 8. Upon rotating the top member 90 degrees in a clockwise direction, the innermost openings 7 will be positioned over the numeral 1 in the area A, indicating 1/% in the innermost opening 7 and its decimal equivalent, viz, .250 in the opening 8. In like manner the areas B, C, D and E contain equally spaced numerators for the denominators with which they are respectively adapted to register. In the marginal area B is printed the decimal equivalent of each fraction as represented by the numerator and in radial alignment therewith. It will thus be seen that when the decimal equivalent of any fraction is desired, it is only necessary to relatively adjust the top and bottom members until the desired fraction is obtained by associating the numerator and denominator, thereby positioning the requisite decimal equivalent in the opening 8. In inverse manner, given any decimal, its fractional equivalent or the one closest for all practical purposes is easily obtainable as will be obvious.

By arranging the denominator openings and the decimal-indicating opening in closely associated relation, the readings may be very quickly obtained and read without liability of confusion or error, and furthermore any closely related fractions or decimals are instantly obtainable. For example, if the decimal equivalent of 1/64tl1 less than 31/32 (shown in Fig. is desired, it is only necessary to shift the top member in a counterclockwise direction to the next succeeding decimal. t will also be noted that the numerators are so arranged that only one at a time may be registered in an opening 7, except in the position shown in Fig. 1.

It is believed that the foregoing conveys a clear understanding of my invention, and while I have illustrated but a single wor ing embodiment thereof, it should be understood that various changes might be made in the shape of the top and bottom members and the arrangement of the printed matter thereon, without departing from the spirit and scope of the invention as expressed in the appended claims, in which I claim;

1. A decimal equivalent chart comprising a top and a bottom member pivotally connected so that one may be revolved with respect to the other, the top member having a series of openings spaced in radial plane and having the following denominators below said openings, spaced from the center outwardly, viz: 4i, 8, 16, 32 and 64., the bottom member having numerator-s for each of said denominators arranged in annular paths coincident with said openings so that said member may be relatively revolved to position any numerator in the opening above its respective denominator, and the bottom member having a decimal equivalent for each numerator in radial alignment therewith, the top member having an opening in proximity to said series of openings and with which each decimal equivalent registers when its respective numerator is in registration with its opening in the top member.

2. A. decimal equivalent chart comprising a top and a bottom member pivotally con- .nected at the center so as to be relatively rotatable, the bottom member having on its "face annular concentric areas divided into predetermined segments reaching from the inner to the outermost areas, each area with the exception of the outermost, containing circumferentially spaced numerators of a given fraction, the largest fraction being in the inner and the smallest in the outermost fraction area, each numerator irrespective of its area being in an independent segment, a decimal equivalent in the outermost area in the segment of its respective numerator, the top member having denominators in substantially radial alignment and overlying their respective numerator areas, the said top member having a radially disposed open portion directly above said denominators and inclusive or" the decimal equivalent in a given segment, whereby any fraction and its decimal equivalent may be shown by adjusting the top member on the bottom member to position the selected numerator over a given denominator of the desired fraction.

3. A decimal equivalent chart comprising a top and a bottom member concentrically connected and relatively rotatable, the bottom member having on its face concentric areas and numerators of certain denominators arranged in said areas, the numerators for the largest fractional denominators being in the innermost area and those for the smaller fractional denominators in each successive outer area, said numerators being equally circumferentially spaced, each in an independent radial plane, said bottom member also having in its outermost areaa decirnal equivalent for each numerator in its 

